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Mercado Apartments - Nodes 3-4 Installation Report

Today volunteers from SoCalFreeNet got together and installed two new nodes at the Mercado Apartment complex. It was also a great training day, with three volunteers lending a hand for the first time. Many thanks to Ben, David, Doug, Drew, Jason, Marc and Pascal for providing their valuable time and expertise!

These two nodes are also a change for us. We had originally planned to simply repeat our node 1 and node 2 installations, but with new equipment coming onto the market all the time, and new software updates becoming available, we decided to try something new. Plus, we like experimenting! Go directly to the photos, or keep reading.

The result so far is very promising. Instead of spending an hour or more configuring pebble via ssh, and then repeating the installation for the second radio, we used the latest release of M0n0wall which now supports Atheros based radios, and hence the 802.11a component of our relay. Initial configuration took about 15 minutes and the second node took less than 5 as we could simply copy the single config file from one node to the other and adjust a couple of settings (wan static IP, WLAN subnet and DHCP range).

We're also using new hardware. WRAP boards have been around for a while, but we've used Soekris more often because of better availability and familiarity. However they are gaining increasing popularity with WISPs and we also obtained one and wrote about it in our recent book, so we were eager to try one. We've recently used Metrix kits instead of building our boxes because they're more convenient, well packaged and well priced. However the arrival of WRAP outdoor cases by Mini-box (see also our recent review) presents an alternative attractive solution. The bundle by Netgate is a convenient way to purchase this, except for the RP-N pigtails and 5 dBi antennas which we didn't use.

The topology of our network is a central 802.11a access point that is connected to the internet. From there we have several 'relay nodes' which receive the 802.11a signal and then supply internet via an 802.11b AP. The buildings at this particular site have walls that kill the 2.4GHz signal very quickly, so we need to have multiple access points even though the actual site size is relatively small. Click the map at right to see the node locations more clearly.

Each node runs in its own subnet and provides DHCP and DNS caching for local 802.11b clients. NAT (aka masq) is not done at the node location, but rather at the central gateway. Avoiding NAT at the node level will allow possibly future applications within the site, plus it allows the main gateway router to provide captive portal services for the entire network and generally centralizes management tasks. Read the network configuration for specifics.

The installation went smoothly. We started the day by reviewing and explaining the equipment in use and then stepping through the m0n0wall configuration we had used. All the equipment had been pre-assembled, mounted on the mast and tested first off-site and then onsite to help ensure that the day would go well.

Next we unpacked tools and lugged the gear over to the proposed location for node 3. Choosing the actual rooftop is a tradeoff between potential future growth of foilage, ease of access to the ground level utility cabinets where the power is and the coverage goals. And, to keep things interesting, it often isn't apparent until you actually get onto the rooftop whether or not a location will be suitable. E.g. for the second installation (node 4) we chose a rooftop from the ground, but then had to switch to an adjacent roof when we discovered intervening palm trees.

At this point we split into ground and rooftop teams. The roof team further split. Marc and Jason concentrated on mounting the radio. Pascal measured, cut and threaded the cat-5 cable and ground wire into conduit and fed it to ground level via the drainpipe.

The ground team took the drop from the drainpipe and routed it around to the utility closet using the flashing at the bottom of the buidling wall which had conveniently located holes for zip ties. The cat-5 cable went inside the utility cabinet to pick up the PoE power and the ground wire continued in the dirt to around to the large water pipe disappearing into the ground.

Click to view the photos below and the associated text with more information.

Equipment Costs

We haven't completed tallying up yet, but the approximate per node cost is $650. This breaks down as: